TY - JOUR

T1 - Photoelectron diffraction for probing valency and magnetism of 4f-based materials: A view on valence-fluctuating EuIr2Si2

AU - Usachov, D. Yu.

AU - Tarasov, A.

AU - Schulz, S.

AU - Bokai, K. A.

AU - Tupitsyn, I. I.

AU - Poelchen, G.

AU - Seiro, S.

AU - Caroca-Canales, N.

AU - Kliemt, K.

AU - Mende, M.

AU - Kummer, K.

AU - Krellner, C.

AU - Muntwiler, M.

AU - Li, Hang

AU - Laubschat, C.

AU - Geibel, C.

AU - Chulkov, E.

AU - Fujimori, S.

AU - Vyalikh, D. V.

N1 - Funding Information: This work was supported by the Russian Foundation for Basic Research (Grant No. 20-32-70127), the Ministry of Science and Higher Education of the Russian Federation [Grant No. 075-15-2020-797 (13.1902.21.0024)], Saint Petersburg State University (Grant No. ID 51126254), and the German Research Foundation (DFG) through Grants No. KR-3831/5-1, No. LA655/20-1, No. GRK1621, No. SFB1143 (Project No. 247310070), and ProjectNo. 422213477–TRR 288. D.V.V. acknowledges financial support from the Spanish Ministry of Economy (MAT-2017-88374-P). E.V.Ch. acknowledges the Tomsk State University competitiveness improvement program (Grant No. 8.1.01.2018). S.I.F. acknowledges Japan Society for the Promotion of Science (KAKENHI Grant No. JP16H01084). We thank the Paul Scherrer Institut, Villigen, Switzerland for provision of synchrotron radiation beamtime at beamlines PEARL and SIS of the SLS. Publisher Copyright: © 2020 American Physical Society.

PY - 2020/11/2

Y1 - 2020/11/2

N2 - We present and discuss the methodology for modeling 4 f photoemission spectra, 4 f photoelectron diffraction (PED) patterns, and magnetic dichroism effects for rare-earth-based materials. Using PED and magnetic dichroism in photoemission, we explore the electronic and magnetic properties of the near-surface region of the valence-fluctuating material EuIr2Si2. For the Eu-terminated surface, we found that the topmost Eu layer is divalent and exhibits a ferromagnetic order below 10 K. The valency of the next Eu layer, that is the fifth atomic layer, is about 2.8 at low temperature that is close to the valency in the bulk. The properties of the Si-terminated surface are drastically different. The first subsurface Eu layer (fourth atomic layer below the surface) behaves divalently and orders ferromagnetically below 48 K. Experimental data indicate, however, that there is an admixture of trivalent Eu in this layer, resulting in its valency of about 2.1. The next deeper lying Eu layer (eighth atomic layer below the surface) behaves mixed valently, but the estimated valency of 2.4 is notably lower than the value in the bulk. The presented approach and obtained results create a background for further studies of exotic surface properties of 4 f -based materials, and allow us to derive information related to valency and magnetism of individual rare-earth layers in a rather extended area near the surface.

AB - We present and discuss the methodology for modeling 4 f photoemission spectra, 4 f photoelectron diffraction (PED) patterns, and magnetic dichroism effects for rare-earth-based materials. Using PED and magnetic dichroism in photoemission, we explore the electronic and magnetic properties of the near-surface region of the valence-fluctuating material EuIr2Si2. For the Eu-terminated surface, we found that the topmost Eu layer is divalent and exhibits a ferromagnetic order below 10 K. The valency of the next Eu layer, that is the fifth atomic layer, is about 2.8 at low temperature that is close to the valency in the bulk. The properties of the Si-terminated surface are drastically different. The first subsurface Eu layer (fourth atomic layer below the surface) behaves divalently and orders ferromagnetically below 48 K. Experimental data indicate, however, that there is an admixture of trivalent Eu in this layer, resulting in its valency of about 2.1. The next deeper lying Eu layer (eighth atomic layer below the surface) behaves mixed valently, but the estimated valency of 2.4 is notably lower than the value in the bulk. The presented approach and obtained results create a background for further studies of exotic surface properties of 4 f -based materials, and allow us to derive information related to valency and magnetism of individual rare-earth layers in a rather extended area near the surface.

KW - RESONANT PHOTOEMISSION

KW - CIRCULAR-DICHROISM

KW - SURFACE

KW - TRANSITION

UR - http://www.scopus.com/inward/record.url?scp=85096105608&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.102.205102

DO - 10.1103/PhysRevB.102.205102

M3 - статья

VL - 102

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 1098-0121

IS - 20

M1 - 205102

ER -